Jan is code format_url function for check https:// and http:// protocol but rational chars is no check. Is say if empty, nothing is show in member profile for user_homepage field but if user enter no valid chars URL type, is still show. E.g: http://www. ... where is full URL ?

1 - No possible for add empty URL, no valid chars or no full URL (http or https - no matter).2 - Save ressource for member editprofile page (USERS_TABLE update SQL query). Empty result is no use action for update SQL query.